Plant manufacturers typically produce mini-loaders with wheels and not tracks as they are not aimed at use on rough and/or soft terrain. By mini-loaders is meant less than 2 to 5 tonnes in weight un-laden. However, it is useful in some circumstances to use such plant in such conditions and in this case the use of continuous tracks is better than wheels. Relatively small (preferably less than 1 metre in length, although other lengths are contemplated) continuous track units may be retro-fitted to such vehicles via the drive hub. However, the vehicles in question have to be used carefully as the track units can shear-off the drive hub through rough use, shock loading and the like.